Soldering apparatus for cable sheathing



D. A. HUGHES Filed may 11', 1955 July 30, 1957 soLDERING APPARATUS ma CABLE SHEATHING SOLDERING APPARATUS FOR CABLE SHEATHING David A. Hughes, Chatham, N. J., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Applieation May 11, 195s, serial No. 501,656

' 4 Claims.V (cl. 219-9.s)

This invention relates to soldering apparatus and has for its object improved apparatus for soldering7 seams in cable sheathing.

The soldering of seams in steel cable sheathing, for example, composite sheath telephone cables as disclosed in Patent 2,589,700, which issued March 18, 1952, to H. G. Johnstone, necessitates heating the metal sheathing to a higher temperature than the conductor insulation can withstand without charring. It is desirable, therefore, to solder the seam by heating the sheathing rapidly and quenching immediately so that excessive heat does not have time to be transmitted to the insulation. When cable is to be soldered by induction heating while moving it, for example, 90 ft. per minute, the heating coil must carry large high frequency currents which give rise to potential differences of considerable magnitude between the coil and the grounded sheathing. Arcing cannot be olehrated as it would ruin the sheath or coil or possibly According to this invention, the coil is shaped to permit placing a water spray shoe close to the cable exit end of the coil and directly connecting this end of the coil to ground thereby preventing the build-up of any potential diiferences at this position where arcing is most apt to occur. There is a very rapid transition from maximum heating to maximum cooling which permits the use of maximum heating currents and cable speed without danger of charring the cable insulation.

These and other features of the invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawing, in which:

Fig. l is a front elevational view of cable sheathing soldering apparatus incorporating the general features of the invention;

Fig. 2 is a perspective view showing the heating coil structure;

Fig.\3 is a cross-sectional view of the water spray shoe, and

Fig. 4 is a sectional view of the cooling shoe through the plane of line 4 4 of Fig. 3.

Referring now to the drawing, the terminal bars 5 and 6 of a step-down transformer 4 are connected to and support an elongated hairpin shaped induction heating coil 7 over the seam 10 of a cable 11 which is normally being moved from left to right as seen in Fig. l. The coil is made rigid by an insulating plate 14 which is bolted to pins 8 extending from the coil. A shoe 3, which rides on the cable is structurally connected to the plate 14 for holding the coil above the cable. This coil positioning apparatus forms the subject matter of applicants co-pending application 507,625, tiled May l1, 1955, and entitled Cable Seam Soldering Apparatus, now Patent No. 2,758,189, dated August 7, 1956. The cable exit end 12 of the elongated coil is squared-off to permit placing a correspondingly squared-off end of a cooling shoe 13 immediately adjacent thereto. By so locating the United States Patent O 2,801,316 Patented July 30, 1957 cooling shoe, maximum transition from heating to cooling is realized which makes it possible to heat the cable sheathing to higher temperatures than was possible heretofore without charring the cable insulation. In view of the increased soldering temperatures permitted with this arrangement, it is possible to speed up the cable line and reduce considerably the time required for soldering the cable seam.

The cooling shoe 13 is resiliently supported on the cable, by an adjustable spring tensioning device 15 mounted to a rigid support member 9, to ride in pressure contact on the cable 11. The shoe is water cooled by means of apertures 22 and 23 and an interconnecting chamber 24 with a conventional circulatory system, not shown. Cooling the shoe is necessary in order to prevent the solder from adhering thereto. In addition, the underside, or cable-contacting side, of the shoe is notched out for spraying cool water on the newly soldered seam 10 in order to quench it immediately after it emerges from the eld of the coil. The water is sprayed directly across the seam to effect maximum cooling out of a plurality of apertures 17 which are fed from a hole 19 which extends along the back side of the shoe, a tube 16 being connected to the hole 19 for supplying water thereto.

The cable is heated principally by the stray flux from the side of the coil located directly above the seam 10 of the cable. Theoretically, for maximum eiciency, the coil should occupy a position parallel to that of the cable passing beneath it, however, in practice it has been found that for best results the coil should be tilted slightly as seen in Fig. l. The squared end of the coil normally occupies the closest position to the cable, especially, as disclosed in the aforementioned co-pending application, when the cable is started in motion at which time the coil is tilted in order to concentrate the heating effect on the cable exit end of the coil. The cable exit end of the coil is connected directly to ground through a grounding conductor 21 for a minimum potential difference between this end of the coil and the cable sheathing. If the normal practice is followed, that is one terminal of the transformer is directly connected to ground, arcing would quite probably occur at this point due to closeness of the coil to the sheath and also the water spray from the adjacent shoe 13, since despite the very low resistance of the coil, the potential difference between the coil and sheath may be high, e. g. 50 volts due to the high current flow in the coil.

It is to be understood that the above described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. Cable seam soldering apparatus comprising an elongated induction heating coil, means for supporting the coil in axial alignment with and above the path of a moving cable, means for energizing the coil, a shoe mounted adjacent to the cable exit end of the coil for dispensing a coolant fluid to the heated seam and a ground lead connected to the exit end of the heating coil to prevent arcing between the coil and the cable.

2. Cable seam soldering apparatus comprising a square ended induction heating coil, means for supporting the coil in axial alignment with and above the path of a moving cable, the square end being the cable exit end of the coil, means for energizing the coil, a square ended cooling shoe mounted adjacent the square end of the coil and a ground connection for the square end of the coil to prevent arcing between the coil and the cable.

3. Cable seam soldering apparatus comprising a square ended induction heating coil, means for supporting the coil in axial alignment with and above the path of a moving cable, the square end being the cable exit end of the coil, means for energizing the coil, a square ended shoe mounted adjacent the square rend of the coil and having a plurality 'of apertures on the underside thereof for spraying water on lthe soldered seam to quench the seam immediately after -itemerges from the "field of the coil and a ground connection for the square end of the coil to prevent arcing between the coil and the cable.

4. Cable seam soldering apparatus comprising asquare ended induction heating coil, lmeans for supporting the coil in axial alignment with an above thepath of a moving cable, the square end being the vcable eXit kend of the coil, Ameans for Venergizing 'the coil, a Water cooled square ended shoe mounted adjacent the square end of the coil `and having a plurality of 'apertures on the underside thereof for spraying water on the soldered seam to quench the seam immediately after it emerges from the eld of the coil and a ground connection for the square end of the coil to prevent arcing between the coil and the cable.

References Cited in the le of this patent UNITED STATES PATENTS 1,480,022 Snodgrass Jan. 8, 1924 2,202,758 Denneen et al. May 28, 1940 2,223,312 Briggs Nov. 26, 1940 2,315,508 Denneen et al. Apr. 6, 1943 2,686,460 Bridge et al. Aug. 17, 1954 

